Patchwork [U-Boot] arm: fix bug on relocation address

login
register
mail settings
Submitter Luca Ellero
Date Jan. 31, 2013, 2:29 p.m.
Message ID <1359642542-18998-1-git-send-email-lroluk@gmail.com>
Download mbox | patch
Permalink /patch/217194/
State Deferred
Delegated to: Albert ARIBAUD
Headers show

Comments

Luca Ellero - Jan. 31, 2013, 2:29 p.m.
If (N. SDRAM banks > 1) and they are not contiguous, don't relocate
u-boot at (CONFIG_SYS_SDRAM_BASE + gd->ram_size), which is a bug.
Instead use the end of 2nd bank (even if there are more than 2 banks)

Signed-off-by: Luca Ellero <lroluk@gmail.com>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>
Cc: Heiko Schocher <hs@denx.de>
---

On ARM architectures there is a bug getting top of SDRAM (where u-boot 
will be relocated). Top of SDRAM will always be:

CONFIG_SYS_SDRAM_BASE + gd->ram_size

anyway this can be wrong since SDRAM can be composed by more that one 
bank in not-contiguous address space.
(CONFIG_SYS_SDRAM_BASE + gd->ram_size) can land to not existent SDRAM 
addresses and can be very dangerous since it can potentially corrupt 
real SDRAM (in most cases SDRAM is aliased so writing to some 
not-existent address can write to real address).
Some arch use more than 2 banks but implementing all macros checks to 
PHYS_SDRAM_* leads to very ugly code, so I think using 2nd bank is good 
and does not generates bloated code


 arch/arm/lib/board.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)
Jeroen Hofstee - Jan. 31, 2013, 7:08 p.m.
Hello Luca,

On 01/31/2013 03:29 PM, Luca Ellero wrote:
> If (N. SDRAM banks > 1) and they are not contiguous, don't relocate
> u-boot at (CONFIG_SYS_SDRAM_BASE + gd->ram_size), which is a bug.
> Instead use the end of 2nd bank (even if there are more than 2 banks)
>
> Signed-off-by: Luca Ellero <lroluk@gmail.com>
> Cc: Albert Aribaud <albert.u.boot@aribaud.net>
> Cc: Heiko Schocher <hs@denx.de>
> ---
>
> On ARM architectures there is a bug getting top of SDRAM (where u-boot
> will be relocated). Top of SDRAM will always be:
>
> CONFIG_SYS_SDRAM_BASE + gd->ram_size
>
> anyway this can be wrong since SDRAM can be composed by more that one
> bank in not-contiguous address space.
I don't think this is a valid use case since the README says:

"The available memory is mapped to fixed addresses using the memory
controller. In this process, a contiguous block is formed for each
memory type (Flash, SDRAM, SRAM), even when it consists of several
physical memory banks."

Regards,
Jeroen
Heiko Schocher - Feb. 1, 2013, 8:17 a.m.
Hello Luca,

on 31.01.2013 15:29, Luca Ellero wrote:
> If (N. SDRAM banks > 1) and they are not contiguous, don't relocate
> u-boot at (CONFIG_SYS_SDRAM_BASE + gd->ram_size), which is a bug.
> Instead use the end of 2nd bank (even if there are more than 2 banks)
> 
> Signed-off-by: Luca Ellero <lroluk@gmail.com>
> Cc: Albert Aribaud <albert.u.boot@aribaud.net>
> Cc: Heiko Schocher <hs@denx.de>
> ---
> 
> On ARM architectures there is a bug getting top of SDRAM (where u-boot 
> will be relocated). Top of SDRAM will always be:
> 
> CONFIG_SYS_SDRAM_BASE + gd->ram_size
> 
> anyway this can be wrong since SDRAM can be composed by more that one 
> bank in not-contiguous address space.
> (CONFIG_SYS_SDRAM_BASE + gd->ram_size) can land to not existent SDRAM 
> addresses and can be very dangerous since it can potentially corrupt 
> real SDRAM (in most cases SDRAM is aliased so writing to some 
> not-existent address can write to real address).
> Some arch use more than 2 banks but implementing all macros checks to 
> PHYS_SDRAM_* leads to very ugly code, so I think using 2nd bank is good 
> and does not generates bloated code

This is not a valid use case for U-Boot! Look in the README
section "Memory Management". This is not so trivial as it looks,
as for example the stack pointer starts somewhere near the end
of RAM and grows downwards. If you now have RAM with gaps, it maybe
reaches an address, which is not valid ...

bye,
Heiko
Luca Ellero - Feb. 1, 2013, 8:50 a.m.
Hi Jeroen,
Hi Heiko,

On 31/01/2013 20.08, Jeroen Hofstee wrote:
> Hello Luca,
>
> On 01/31/2013 03:29 PM, Luca Ellero wrote:
>> If (N. SDRAM banks > 1) and they are not contiguous, don't relocate
>> u-boot at (CONFIG_SYS_SDRAM_BASE + gd->ram_size), which is a bug.
>> Instead use the end of 2nd bank (even if there are more than 2 banks)
>>
>> Signed-off-by: Luca Ellero <lroluk@gmail.com>
>> Cc: Albert Aribaud <albert.u.boot@aribaud.net>
>> Cc: Heiko Schocher <hs@denx.de>
>> ---
>>
>> On ARM architectures there is a bug getting top of SDRAM (where u-boot
>> will be relocated). Top of SDRAM will always be:
>>
>> CONFIG_SYS_SDRAM_BASE + gd->ram_size
>>
>> anyway this can be wrong since SDRAM can be composed by more that one
>> bank in not-contiguous address space.
> I don't think this is a valid use case since the README says:
>
> "The available memory is mapped to fixed addresses using the memory
> controller. In this process, a contiguous block is formed for each
> memory type (Flash, SDRAM, SRAM), even when it consists of several
> physical memory banks."
>

Thank for your comments.
You are saying more or less the same thing but I'm afraid I didn't 
really catch what you mean.
I know how is the U-Boot memory map and I summarize it here  (more or 
less, depending on board configuration):

TOP of RAM ------------------------
              Kernel Log Buffer
            ---------------------------
              Protected RAM
            ---------------------------
              TLB Table (32kB to 64 kB)
            ---------------------------
              LCD Frame Buffer
            ---------------------------
              Relocated U-Boot Code
            ---------------------------
              malloc area
            ---------------------------
              Board Info (struct bd_t)
            ---------------------------
              Global Data (struct gd_t)
            ---------------------------
              IRQ Stack
            ---------------------------
              Abort Stack
            ---------------------------
	     ...


Now, I have a Freescale iMX53 LOCO board which have 2 banks of 512 MB 
SDRAM, for total of 1GB. One bank is at phys 0x70000000-0x8fffffff, the 
other is at 0xb0000000-0xcfffffff.
If I stop U-Boot execution after relocation (with a JTAG debugger) I see 
that it is running at physical address 0xaff6D000 (more or less).
As far as I can see this address is not existent. And the dangerous part 
is that I can see the same data (U-Boot code) at address 0x8ff6D000. 
This clearly states that U-Boot is relocated at 0xAff6D000
but in reality it is at 0x8ff6D000 an the relocation can potentially 
override data already existing there.
Don't you think this is a wrong behaviour?
Thanks
Regards
Luca
Luca Ellero - Feb. 1, 2013, 9:49 a.m.
Hi,

On 01/02/2013 11.07, Heiko Schocher wrote:
> Hello Luce,
>
> Am 01.02.2013 09:50, schrieb Luca Ellero:
>> Hi Jeroen,
>> Hi Heiko,
>>
>> On 31/01/2013 20.08, Jeroen Hofstee wrote:
>>> Hello Luca,
>>>
>>> On 01/31/2013 03:29 PM, Luca Ellero wrote:
>>>> If (N. SDRAM banks > 1) and they are not contiguous, don't relocate
>>>> u-boot at (CONFIG_SYS_SDRAM_BASE + gd->ram_size), which is a bug.
>>>> Instead use the end of 2nd bank (even if there are more than 2 banks)
>>>>
>>>> Signed-off-by: Luca Ellero <lroluk@gmail.com>
>>>> Cc: Albert Aribaud <albert.u.boot@aribaud.net>
>>>> Cc: Heiko Schocher <hs@denx.de>
>>>> ---
>>>>
>>>> On ARM architectures there is a bug getting top of SDRAM (where u-boot
>>>> will be relocated). Top of SDRAM will always be:
>>>>
>>>> CONFIG_SYS_SDRAM_BASE + gd->ram_size
>>>>
>>>> anyway this can be wrong since SDRAM can be composed by more that one
>>>> bank in not-contiguous address space.
>>> I don't think this is a valid use case since the README says:
>>>
>>> "The available memory is mapped to fixed addresses using the memory
>>> controller. In this process, a contiguous block is formed for each
>>> memory type (Flash, SDRAM, SRAM), even when it consists of several
>>> physical memory banks."
>>>
>>
>> Thank for your comments.
>> You are saying more or less the same thing but I'm afraid I didn't
>> really catch what you mean.
>
> You have 2 memory banks which are not contiguos.
>
> [...]
>> Now, I have a Freescale iMX53 LOCO board which have 2 banks of 512 MB
>> SDRAM, for total of 1GB. One bank is at phys 0x70000000-0x8fffffff, the
>> other is at 0xb0000000-0xcfffffff.
>
> Here you have a gap from 0x90000000 - 0xafffffff between the two banks,
> which U-Boot currently not supports ...
>
>> If I stop U-Boot execution after relocation (with a JTAG debugger) I see
>> that it is running at physical address 0xaff6D000 (more or less).
>> As far as I can see this address is not existent. And the dangerous part
>> is that I can see the same data (U-Boot code) at address 0x8ff6D000.
>> This clearly states that U-Boot is relocated at 0xAff6D000
>> but in reality it is at 0x8ff6D000 an the relocation can potentially
>> override data already existing there.
>> Don't you think this is a wrong behaviour?
>
> This wrong behaviour results because you use U-Boot in a
> configuration, which U-Boot currently not handle correct resp.
> does not support ...
>
> Why you need such a memory configuration?
>
> I suggest to move the second bank (if possible) to 0x90000000
> and you have a contiguos memory, and U-Boot should work fine.
>

That's exactly the point!!!
As far as I know iMX53 _can't_ physically move banks to other addresses.
And likely there are some other architectures that have the same behaviour.
Maybe someone on the list can confirm this.
Bye
Luca
Heiko Schocher - Feb. 1, 2013, 10:07 a.m.
Hello Luce,

Am 01.02.2013 09:50, schrieb Luca Ellero:
> Hi Jeroen,
> Hi Heiko,
> 
> On 31/01/2013 20.08, Jeroen Hofstee wrote:
>> Hello Luca,
>>
>> On 01/31/2013 03:29 PM, Luca Ellero wrote:
>>> If (N. SDRAM banks > 1) and they are not contiguous, don't relocate
>>> u-boot at (CONFIG_SYS_SDRAM_BASE + gd->ram_size), which is a bug.
>>> Instead use the end of 2nd bank (even if there are more than 2 banks)
>>>
>>> Signed-off-by: Luca Ellero <lroluk@gmail.com>
>>> Cc: Albert Aribaud <albert.u.boot@aribaud.net>
>>> Cc: Heiko Schocher <hs@denx.de>
>>> ---
>>>
>>> On ARM architectures there is a bug getting top of SDRAM (where u-boot
>>> will be relocated). Top of SDRAM will always be:
>>>
>>> CONFIG_SYS_SDRAM_BASE + gd->ram_size
>>>
>>> anyway this can be wrong since SDRAM can be composed by more that one
>>> bank in not-contiguous address space.
>> I don't think this is a valid use case since the README says:
>>
>> "The available memory is mapped to fixed addresses using the memory
>> controller. In this process, a contiguous block is formed for each
>> memory type (Flash, SDRAM, SRAM), even when it consists of several
>> physical memory banks."
>>
> 
> Thank for your comments.
> You are saying more or less the same thing but I'm afraid I didn't 
> really catch what you mean.

You have 2 memory banks which are not contiguos.

[...]
> Now, I have a Freescale iMX53 LOCO board which have 2 banks of 512 MB 
> SDRAM, for total of 1GB. One bank is at phys 0x70000000-0x8fffffff, the 
> other is at 0xb0000000-0xcfffffff.

Here you have a gap from 0x90000000 - 0xafffffff between the two banks,
which U-Boot currently not supports ...

> If I stop U-Boot execution after relocation (with a JTAG debugger) I see 
> that it is running at physical address 0xaff6D000 (more or less).
> As far as I can see this address is not existent. And the dangerous part 
> is that I can see the same data (U-Boot code) at address 0x8ff6D000. 
> This clearly states that U-Boot is relocated at 0xAff6D000
> but in reality it is at 0x8ff6D000 an the relocation can potentially 
> override data already existing there.
> Don't you think this is a wrong behaviour?

This wrong behaviour results because you use U-Boot in a
configuration, which U-Boot currently not handle correct resp.
does not support ...

Why you need such a memory configuration?

I suggest to move the second bank (if possible) to 0x90000000
and you have a contiguos memory, and U-Boot should work fine.

bye
Heiko
Luca Ellero - Feb. 7, 2013, 9:07 a.m.
Hi all,

On 01/02/2013 10.49, Luca Ellero wrote:
> Hi,
>
> On 01/02/2013 11.07, Heiko Schocher wrote:
>> Hello Luce,
>>
>> Am 01.02.2013 09:50, schrieb Luca Ellero:
>>> Hi Jeroen,
>>> Hi Heiko,
>>>
>>> On 31/01/2013 20.08, Jeroen Hofstee wrote:
>>>> Hello Luca,
>>>>
>>>> On 01/31/2013 03:29 PM, Luca Ellero wrote:
>>>>> If (N. SDRAM banks > 1) and they are not contiguous, don't relocate
>>>>> u-boot at (CONFIG_SYS_SDRAM_BASE + gd->ram_size), which is a bug.
>>>>> Instead use the end of 2nd bank (even if there are more than 2 banks)
>>>>>
>>>>> Signed-off-by: Luca Ellero <lroluk@gmail.com>
>>>>> Cc: Albert Aribaud <albert.u.boot@aribaud.net>
>>>>> Cc: Heiko Schocher <hs@denx.de>
>>>>> ---
>>>>>
>>>>> On ARM architectures there is a bug getting top of SDRAM (where u-boot
>>>>> will be relocated). Top of SDRAM will always be:
>>>>>
>>>>> CONFIG_SYS_SDRAM_BASE + gd->ram_size
>>>>>
>>>>> anyway this can be wrong since SDRAM can be composed by more that one
>>>>> bank in not-contiguous address space.
>>>> I don't think this is a valid use case since the README says:
>>>>
>>>> "The available memory is mapped to fixed addresses using the memory
>>>> controller. In this process, a contiguous block is formed for each
>>>> memory type (Flash, SDRAM, SRAM), even when it consists of several
>>>> physical memory banks."
>>>>
>>>
>>> Thank for your comments.
>>> You are saying more or less the same thing but I'm afraid I didn't
>>> really catch what you mean.
>>
>> You have 2 memory banks which are not contiguos.
>>
>> [...]
>>> Now, I have a Freescale iMX53 LOCO board which have 2 banks of 512 MB
>>> SDRAM, for total of 1GB. One bank is at phys 0x70000000-0x8fffffff, the
>>> other is at 0xb0000000-0xcfffffff.
>>
>> Here you have a gap from 0x90000000 - 0xafffffff between the two banks,
>> which U-Boot currently not supports ...
>>
>>> If I stop U-Boot execution after relocation (with a JTAG debugger) I see
>>> that it is running at physical address 0xaff6D000 (more or less).
>>> As far as I can see this address is not existent. And the dangerous part
>>> is that I can see the same data (U-Boot code) at address 0x8ff6D000.
>>> This clearly states that U-Boot is relocated at 0xAff6D000
>>> but in reality it is at 0x8ff6D000 an the relocation can potentially
>>> override data already existing there.
>>> Don't you think this is a wrong behaviour?
>>
>> This wrong behaviour results because you use U-Boot in a
>> configuration, which U-Boot currently not handle correct resp.
>> does not support ...
>>
>> Why you need such a memory configuration?
>>
>> I suggest to move the second bank (if possible) to 0x90000000
>> and you have a contiguos memory, and U-Boot should work fine.
>>
>
> That's exactly the point!!!
> As far as I know iMX53 _can't_ physically move banks to other addresses.
> And likely there are some other architectures that have the same behaviour.
> Maybe someone on the list can confirm this.
> Bye
> Luca

Any news here?
If this patch isn't the proper way to fix this misbehaviour, please 
suggest some other way to correct it. I'm a bit scary of viewing code 
running in "not-existing" addresses :-)
Thanks
Regards
Luca

Patch

diff --git a/arch/arm/lib/board.c b/arch/arm/lib/board.c
index 9f861cc..98634ab 100644
--- a/arch/arm/lib/board.c
+++ b/arch/arm/lib/board.c
@@ -333,7 +333,19 @@  void board_init_f(ulong bootflag)
 	gd->ram_size -= CONFIG_SYS_MEM_TOP_HIDE;
 #endif
 
+#if defined(PHYS_SDRAM_2) && defined(PHYS_SDRAM_2_SIZE)
+	if (CONFIG_NR_DRAM_BANKS > 1 &&
+		(PHYS_SDRAM_1 + PHYS_SDRAM_1_SIZE) != PHYS_SDRAM_2)
+		addr =  PHYS_SDRAM_2 + PHYS_SDRAM_2_SIZE;
+	else
+		addr = CONFIG_SYS_SDRAM_BASE + gd->ram_size;
+#else
 	addr = CONFIG_SYS_SDRAM_BASE + gd->ram_size;
+#endif
+
+
+
+
 
 #ifdef CONFIG_LOGBUFFER
 #ifndef CONFIG_ALT_LB_ADDR